Laryngoscopes are medical devices which are employed to introduce endotracheal tubes into patient's airways, for example, when a patient is being anaesthetised. Laryngoscopes comprise insertion sections, which are the part of a laryngoscope which extends towards and into a patient's oral cavity during intubation. Insertion sections may be removably attachable to a laryngoscope body, integral parts of laryngoscopes or themselves function as laryngoscopes. As well as an insertion section, laryngoscopes typically comprises a handle which is usually elongate and which may be arranged at an angle to the proximal end of the insertion section or generally parallel to the proximal end of the insertion section, or at any angle therebetween. Laryngoscopes further include a source of light and the invention relates to insertion sections for laryngoscopes which further include an image collector. The image collector might collect video images and may, for example, be a video camera or a fibre-optic bundle for conducting an image to an external video camera, arranged to enable a user to view the distal tip of an endotracheal tube as it is being introduced into a patient's larynx. Laryngoscopes which collect video images are referred to as video laryngoscopes. However, laryngoscopes may also include image collectors which are the distal tip of an imaging arrangement including optical components such as one or more prisms or mirrors, to enable intubation to be viewed by eye, without use of a camera.
Video laryngoscope insertion sections may have integral image collectors, for example, an image collector located on the surface of the insertion section. However, light permeable laryngoscope insertion sections may be demountably attachable to an insertion section retaining member of the laryngoscope and the laryngoscope may comprise an image collector operable to receive images through a light permeable and typically transparent region of a demountable attachable insertion section. Video laryngoscopes may include a display for displaying images collected by the image collector, or an output for communication images to an external display device.
Traditional laryngoscope insertion sections, such as insertion sections known in the art as Miller, Macintosh or Wisconsin blades, function to lift a patient's tissue adjacent the epiglottis to enable a tube to be inserted into a patient's larynx and to enable the patient's larynx to be viewed during intubation. However, they do not guide tubes as such.
It has been proposed to provide laryngoscope insertion sections with tube guides, for example lateral tube guides. By a lateral tube guide we refer to a tube guide which guides an endotracheal tube along a lateral side of the insertion section along at least the majority of the length of the insertion section, to the location from where a retained endotracheal tube extends distally from the tube guide. Lateral tube guides are preferable to tube guides located on the inferior surface (i.e. the surface facing a patient's tongue in use) of an insertion section as they reduce bulk in a plane parallel to a patient's midsagittal plane in use.
A video laryngoscope having an insertion section with a lateral tube guide is disclosed in GB 2 431 539 (Pentax). A laryngoscope having an insertion section with a lateral tube guide is also known from WO 04/073510 (Gandarias), although this publication does not disclose a video laryngoscope. Insertion sections for video laryngoscopes having lateral tube guides are also disclosed in our co-pending international application PCT/GB2008/002900.
A disadvantage of known video laryngoscope insertion sections with lateral tube guides relates to the orientation at which a retained tube extends from the distal end of the insertion section. When adding a lateral tube guide to an insertion section which includes an image collector or through which an image collector gathers images, it is natural to add the tube guide to the side of the image collector. This is particularly true when using an image collector which is integral to an endoscope. Thus, proposed configurations have an optical arrangement as shown in FIGS. 6 and 7, in which the centre of the field of view of the image collector and the line along which the tube guide guides an endotracheal tube from the distal end of the insertion section are each at an angle to the median plane of the insertion section, so as to converge at approximately the location of a patient's larynx in use.
However, there are a number of disadvantages associated with this arrangement. Firstly, users of laryngoscopes have typically been trained using conventional Macintosh laryngoscopes and are used to holding an endotracheal tube (which is typically inherently gently curved) in their free hand and introducing it using a smooth curving motion. Accordingly, the movement which is required to advance the tube along the tube guide is not a natural movement. Secondly, the distal tip of the endotracheal tube appears to move both sideways and upwards simultaneously in the field of view of the image collector. This can make it more difficult for a user to be confident that a retained endotracheal tube is being guided along the correct path to be inserted into the larynx. Thirdly, in some patient's the larynx will be further anterior of the epiglottis than normal. In such patient's a tube guide which advances a tube at an angle to a patient's midline will not advance the tube into the patient's larynx without undesirable manipulation. Furthermore, the endotracheal tube is guided along a path including at least some curvature in a lateral direction. This curvature leads to a resistance to movement of the endotracheal tube in a distal direction. As a result, insertion of the endotracheal tube is made more difficult.
Thus, the invention aims to provide laryngoscopes (typically video laryngoscopes) with tube guides and insertion sections with tube guides for laryngoscopes (typically video laryngoscopes) which overcome some or all of these problems.